Year	mm Hg
1980	131.8
1981	132.1
1982	132.4
1983	132.6
1984	132.9
1985	133.1
1986	133.2
1987	133.3
1988	133.3
1989	133.2
1990	133.1
1991	132.9
1992	132.5
1993	132
1994	131.5
1995	131.1
1996	131
1997	131
1998	131.1
1999	131.2
2000	131.5
2001	131.8
2002	132.1
2003	132.3
2004	132.6
2005	132.8
2006	133
2007	133.1
2008	133.3